Final Fantasy XIV Extreme Mode Titan is a full party of 8 players. The average item level should be 67. Of course, the higher the better. Among the three Primals, Garuda, Titan and Ifrit, Titan should be the most difficulty challenge. There battle can be divided into four phases. And the reward should be 25 Tomes of Philosophy, 22 Tomes of Mythology and item level 90 accessory Earrings. You may find it interested FFXIV ARR Extreme Mode Garuda Guides.
Phase one: Landslide (1 way)-> Weight of Land (Plumes)-> Mountain Buster -> Stomps (4 times)-> Repeat
This is the preparation of the following fight. Mountain buster would Debuff the target Tank and could stack every time hit by it. The physical damage taken would be increased. So swap Tank at 2 stacks. If you are a Paladin, pop Rampart as plumes appear because Mountain Buster is coming. If you are an off tank, Provoke to get aggro when you see two Debuffs on the main Tank.
Phase two: Geocrushcrush (Transition) -> Landslide (3 way) -> Granite Gaol*2 -> Mountain Buster -> Upheaval -> Landslide -> Stomps*4 -> Weight of Land -< Mountain Buster -> Landslide -> Weight of Land -> Bombs-> Mountain Buster -> Landslide ->Gaols
At this phase, Landslide would increased to three directions. Gaols would usually prison one Healer and one DPS. The jailed player would not able to move and attack. So other players should help them and break the Gaol as soon as possible. Or they would die.
Phase three (Heart):
Geocrush -> Weight of Land -> Gaol -> Upheaval ->Landslide -> Stomps -> Weight of Land -> Mountain Buster -> Bombs -> Landslide -> Stomps -> Weight of Land -> Earthen Fury
Phase four: (Final) Granite Goalers -> Mountain Buster -> Bombs -> Landslide -> Weight of Land -> Gaol -> Mountain Buster ->Upheaval -> Landslide -> Mountain Buster -> Stomps -> DBL Weight of Land -> Mountain Buster -> Row Bombs Busters -> Landslide -> Mountain Buster -> Super Bombs